A Novel PWM High Voltage Conversion Ratio Bidirectional Three-Phase DC/DC Converter With Y–Δ Connected Transformer

Abstract

In order to solve the problem of high voltage conversion ratio between DC bus and energy storage unit, a novel bi-directional three-phase DC/DC converter applicable to high power condition is proposed in this paper. With the new PWM strategy and inherent ability of increasing voltage conversion ratio of Y-Δ connected transformer, the voltage conversion ratio is doubled. With the new PWM strategy, the effective duty cycle range of three-phase DC/DC converter is expanded, which results in halved filter inductance. Three-phase full-bridge structure is connected to the DC bus, while current-tripler unit is connected to the battery. As three-phase interleaved structure is adopted, not only current stress of switches decreases, but also the frequency of input and output current ripple increases to three times of switching frequency, which leads to smaller filters and extended lives cycle of batteries. The operating principle and characteristics of the converter are analyzed in detail. A prototype with the 360V DC bus converted to 48V/42A batteries was built and the results are given based on the experiments. Index Terms-high voltage conversion ratio, three-phase DC/DC converter, bi-directional DC/DC converter, Y-Δ connected transformer, interleaved Ke Jin (S'04-M'09) was born in Nanjing, China, in 1978. He received the B.S., M.S., and Ph.D. degrees in electrical engineering from the Nanjing University of

Bidirectional isolated three‐phase dc‐dc converter using coupled inductor for dc microgrid applications

“…In Figure 10A, it can be seen that the proposed topology operates perfectly with a full range of duty cycle, providing dc voltage gain without limited duty cycle operation when compared with available literature in 23,26,51,52 . On the other hand, the dc voltage gain of the presented converters in previous works of literature 23,26,51,52 is higher than the proposed topology when the duty cycle is above one‐third. According to Figure 10B, it can be observed that in CCM, the proposed converter has a higher dc voltage gain than the presented converters in previous studies 23,26,51,52 .…”

“…Figure 10 shows the comparing result of dc voltage gain for bidirectional three‐phase dc‐dc converters and the proposed topology for n S = 2 and n T = 5. In Figure 10A, it can be seen that the proposed topology operates perfectly with a full range of duty cycle, providing dc voltage gain without limited duty cycle operation when compared with available literature in 23,26,51,52 . On the other hand, the dc voltage gain of the presented converters in previous works of literature 23,26,51,52 is higher than the proposed topology when the duty cycle is above one‐third.…”

“…Generally, in dc microgrid, when the voltage difference between the battery bank, ultracapacitor, and the dc bus is large, a bidirectional dc‐dc converter with a high dc voltage gain is mandatory 19–21 . The most of references that are focused on three‐phase bidirectional dc‐dc converters (TBDCs) are characterized by a current‐fed or voltage‐fed on one side 22–26 . Based on the placement of auxiliary ES, TBDCs can be classified as step‐down and step‐up type.…”

Conversor CC–CC Bidirecional Push-Pull / Flyback

“…Submetendo (19) em (18) e aplicando o princípio da conservação da energia (W E2 = W R1 ), obtém-se o ganho estático no sentido inverso do fluxo de potência para o MCD em (20). A corrente de saída normalizada (I 1 ) agora é definida como:…”

“…Atualmente, em aplicações onde fontes de baixa tensão e elevada corrente são requeridas, topologias com características de alimentação em corrente e isolamento galvânico, que utilizam transformador trifásico são mais apropriadas e uma alternativa ao clássico conversor DAB trifásico, conforme abordado por [15]- [18]. O conversor possui uma das entradas com características de fonte de corrente e a outra como fonte de tensão, permite aplicar alto ganho de tensão, tem reduzido número de interruptores ativos e um baixo volume de elementos armazenadores de energia (indutor e capacitor) pelo efeito da multiplicação da ondulação de tensão e corrente sobre estes filtros [19].…”